Catheterization of peripheral vasculature is performed generally using a method originally described by Seldinger or a modified Seldinger method.
According to the Seldinger method, an introducer needle is first inserted into a target vein. Bleeding from the needle indicated placement in the vessel. Alternatively, a syringe maybe attached to the needle (FIGS. 1A-1B). Aspiration of the syringe ensures proper placement of the needle within the vein. The syringe is then removed (FIGS. 1C-1D). A guidewire is fed through the introducer needle and into the target vein (FIG. 1E). The introducer needle is then removed, leaving the guidewire in the target vein (FIG. 1F). The guidewire is advanced until it reaches the desired location, e.g., the caval atrial junction. The proximal end of the guidewire is inserted into the distal tip of a catheter lumen. The catheter is fed into the target vein over the guidewire. The catheter is advanced along the guidewire until the distal tip is correctly positioned in the target vein. The guidewire is gently withdrawn. The catheter remains in the target vein.
According to the modified Seldinger method, after the advancement of the guidewire and removal of the introducer needle, a tear-away sheath/dilator assembly is threaded over the proximal end of the guidewire and into the target vein (FIGS. 1G-1H). The dilator is then removed from the sheath (FIG. 1I). The distal tip of catheter is inserted into and through the sheath until the catheter tip is correctly positioned in the target vein (FIG. 1J). The tear-away sheath is then removed by slowly pulling it out of the vessel while simultaneously splitting the sheath. The guidewire is gently withdrawn, leaving the catheter in the target vein (FIG. 1K). Alternatively, the guidewire is withdrawn with the dilator, and the catheter is inserted into the target vein through the sheath.
Catheterization may also be performed using the over-the-needle (OTN) method. According to this method, a tear-away sheath is placed directly exterior to the introducer needle. The tear-away sheath and the introducer needle are inserted simultaneously into the target vein. This method does not typically use a guidewire. A catheter is advanced into the target vein through the sheath.
For neonatal and pediatric applications, because the target vasculature is usually very small and tortuous, specially adapted devises are required to facilitate catheterization while minimizing the risk of vessel trauma. Existing types of small guidewire, typically are complex, and are only available such as neurovascular wires. There exists a need for a vascular guidewire specially adapted for the catheterization of small vasculature and other small tracts and cavities. There is a need for a miniature vascu-sheath and dilator specially adapted for the catheterization of small vasculature and other small tracts and cavities. There is also a need for a specially adapted alignment adaptor to facilitate the manipulation of such guidewire. Further, the specially adapted devices call for a novel method of use.